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GHSA-fmx4-26r3-wxpf

HighCVSS 8.8 / 10
Published Mar 3, 2022·Last modified Feb 4, 2026
Affected Components(0)

No affected components available

Description

Impact

CommonMarker uses cmark-gfm for rendering Github Flavored Markdown. An integer overflow in cmark-gfm's table row parsing may lead to heap memory corruption when parsing tables who's marker rows contain more than UINT16_MAX columns. The impact of this heap corruption ranges from Information Leak to Arbitrary Code Execution.

If affected versions of CommonMarker are used for rendering remote user controlled markdown, this vulnerability may lead to Remote Code Execution (RCE).

Patches

This vulnerability has been patched in the following CommonMarker release:

  • v0.23.4

Workarounds

The vulnerability exists in the table markdown extensions of cmark-gfm. Disabling any use of the table extension will prevent this vulnerability from being triggered.

References

  • https://github.com/github/cmark-gfm/security/advisories/GHSA-mc3g-88wq-6f4x

Acknowledgements

We would like to thank Felix Wilhelm of Google's Project Zero for reporting this vulnerability

For more information

If you have any questions or comments about this advisory:

Risk Scores
Base Score
8.8

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker needs basic access or low-level privileges. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a high impact on the availability of the system.

Threat Intelligence
8.1

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
1.45%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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